Spirometric performance in Belgian Blue calves: I. Effects on economic losses due to the bovine respiratory disease complex

The aim of this study was to determine whether high spirometric performance s in calves are associated with low economic losses due to the bovine respi ratory disease complex (BRDC). Five spirometric variables (SV) were measure d in 909 double-muscled Belgian Blue calves from 15 to 60 d of age. Afterwa rd, calves were monitored for 6 mo to determine whether they developed BRDC and to determine the costs due to BRDC (i.e., medicine costs and veterinar ians' fees, plus estimated financial losses due to mortality in case of dea th). To analyze the effects of spirometric performances on BRDC cost, a fix ed linear model was used for each SV. In addition to SV, each model include d the effects of sex, dam's parity, vaccination status, muscular developmen t score, herd-period, and BW. Only herd-period and the maximal ventilation and the vital capacity had significant effects on costs due to BRDC, indica ting that these two SV are major physiological determinants of economic los ses associated with BRDC. Accordingly, it is assumed that an amelioration o f maximal ventilation and vital capacity could result in increased resistan ce to BRDC in calves.